The present invention relates to an improvement in developing devices for an electrostatic recording device--such as an electrophotographic copying machine--wherein a dry-type developer comprising toner and carrier is used.
In a developing device using dry-type developer comprising toner and carrier, the developer component that is mainly consumed in the copying operations is toner, and thus only toner need generally be replenished in the developer mixture. In conventional developing devices, toner is supplied directly into the developing device from a replenishing hopper to accomplish the replenishment operation. Despite the presence of a simple mixing device, it takes time for the added or replenishment toner to mix with the developer in the developing device; thus, when the developer is then successively conveyed by a developer carrying means (such as a sleeve well known in the art) to the photosensitive member, the conveyed developer occassionally remains in an insufficiently mixed or undispersed state causing an unstable toner density balance for copying.